title: Prenatal exposure to diethylstilbestrol: ovarian-independent growth of mammary tumors induced by 7,12-dimethylbenz[a]anthracene.
abstract: The effects of ovariectomy on the growth of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors were investigated after rats ahd been exposed prenatally to diethylstilbestrol (DES). Pregnant rats were inoculated with either DES (total dose: 1.2 micrograms) in sesame oil or with the vehicle alone on days 10 and 13 of gestation. Female offspring were given 2 gastric intubations of DMBA (10 mg each) 1 week apart beginning at 50 plus or minus 1 days of age. When the average diameter of a mammary tumor exceeded 2 cm, the animal was ovariectomized. The initial response of most tumors in both the DES-exposed and control groups to ovariectomy was size regression. The growth of 7 tumors that arose soon after DMBA treatment in each group was studied for 12-20 weeks after ovariectomy. Whereas only 1 tumor from the control group resumed active growth after the initial regression period, 6 tumors in the DES-exposed group overcame the initial effects of ovariectomy and began to grow again. Thus ovariectomy appeared to be less effective in producing sustained control growth in DMBA-induced mammary tumors in rats exposed prenatally to DES.
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000230:Adenocarcinoma / Q000139:chemically induced; D000232:Adenofibroma / Q000139:chemically induced; D000818:Animals; D002369:Castration; D004054:Diethylstilbestrol; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced* / Q000473:pathology; D008431:Maternal-Fetal Exchange; D010053:Ovary / Q000502:physiology*; D011247:Pregnancy; D011379:Prognosis; D051381:Rats; D013997:Time Factors
chemical_list: D015127:9,10-Dimethyl-1,2-benzanthracene; D004054:Diethylstilbestrol